https://www.teamviewer.com/en/
As today, this seems to be still free for personal use.
But they may have recently split version, and you should pehraps reinstall the very last and dedicated Free version
Maybe updated free binaries are only available for Windows, for the Linux binary (if you use the Linux version) I don't know
Other possible interpretation : for any good or bad reasons, they consider that you are infringing the Free license policy. Possibly, they do statistics, and if they detect number of connection for a given client they consider that this client does business.