The fake text from Venmo below, which claims your account has been locked due to suspicious activity, is a scam. The link in the scam text goes to a phishing website that steals account credentials, personal and financial information.
The Text From Venmo Scam

Venmo,
Your Venmo account has been locked, because we've detected suspicious activity on Venmo your account.
Recovery your Venmo account immediately by click link bellow: https://.../venmoauth-to?=https://venmo.com
Please take action on your account within 48 hours to avoid permanent suspension.
Best Regards,
Venmo Inc.
If you were tricked by the Venmo scam text into disclosing your information, please contact Venmo for help.