On the night of Dec. 9, New York–based movie producer Michael Liu was on his phone, playing Venmo ping-pong with a friend. He bought a photography book earlier that day and had it signed by the author. He gave it to his friend, who is a fan. “I insisted it was a Christmas gift,” Liu told BuzzFeed News. “She sent a Venmo for $85 to me; I sent it back. She tried again, and I sent it back again.” Immediately after the last transaction, Liu’s phone was bombarded with dozens of requests from strangers, both for money and to connect on the app.

The payment request spammers were seemingly targeting users who had made public transactions in the hopes that some of the requests would be granted.

While declining them, he was careful not to tap the “pay” button. “I imagine if [the request] is successful on accident, they can make some good money,” Liu said.

One account that spammed Liu goes by the name “morgan wise.” Its avatar is a screenshot from musician Maggie Lindemann’s Snapchat, and the profile showed no friends or public payments are associated with it. Other profile pictures from the spammers, Liu said, appeared to be taken from Instagram models

BuzzFeed News spoke to three people who’ve recently experienced the same deluge of Venmo requests, ranging from $1 to $100, primarily from accounts whose pictures were of women. All of them had one thing in common: The notifications immediately followed a public transaction on Venmo.

Conner Grant of Boston was in a work meeting when the requests started flying in. “I was a little nervous my account was compromised,” Grant told BuzzFeed News.

But his account wasn’t hacked. A friend had just completed Grant’s Venmo request after a night of drinks, which seemingly prompted the flood of alerts. Grant reached out to Venmo, and in an email dated Dec. 5, a support agent named Alex B. wrote, “Thank [sic] for making us aware of this activity. Recently Venmo was featured in a viral video that encouraged users to connect with other users on the public feed.” Instructions to decline the requests and change the privacy setting for future payments were included below.

A spokesperson for the company declined to comment on the “viral video,” or specify what the video was or where it was shared. After this story’s publication, BuzzFeed News readers pointed to a TikTok, “how to get a venmo sugardaddy eventually,” uploaded by user @d1alcoholic on Nov. 26, which was featured in the app’s Discover section. The TikTok instructs users to “throw up a nice profile pic,” go on Venmo World, “find literally ANY dude that’s online,” and request $1 from them with the comment, “hey ;).”

In a statement, they said, “Venmo’s user agreement expressly prohibits harassment. We treat this matter seriously and will review and take action on accounts that are found to break these policies.” A number of other Venmo users have complained about the same issue on Twitter.

Another Venmo user, Orlando-based John Papa, signed up for the service in October to pay a pet trainer who only accepts payments through the app. Since then, Papa’s received over 30 requests from people he doesn’t know. He didn’t realize that all his Venmo transactions were set to public. “I assumed it would be private or friends only. That would be my suggestion for them. Default to private,” he said.

Transactions set to public, unbeknownst to many users, are broadcast to everyone on Venmo in a public feed. Many privacy researchers say the feed is problematic. My colleague Katie Notopolous has called for Venmo to get rid of it. The app doesn’t reveal the number of public payments, but it does show the payment’s description and who paid whom, with links to each user’s profile.

Venmo offers its users three options for transaction visibility: public, friends only, and private. The setting is set to public when you sign up. Users need to go into the app’s privacy settings to set their default to private, under which payments are only visible to the sender and recipient.

Making payments private is a good way to mitigate spam. Here’s how to do it: In the app, tap the menu icon in the upper-left corner, then Settings. Select Privacy, and under “Default Privacy Setting,” choose Private. While you’re there, tap on Past Transactions below, and then select Change All to Private to retroactively make all payments private.