Change your browser. Most browsers, including the big one - Chrome, do not respect your privacy. They watch and log everything you do, to better target you with ads. Sometimes they pass your (anonymised) data on to others. Switch to Brave, Librewolf or Mulvad. Firefox is ok if you "harden" it by changing some settings and install a few extensions.
Change your email provider. This does take some effort, so keep your old one available for a while you make the switch. Most free online services train AI on your email data, or at least use it to fire more relavent ads at you. Proton Mail is really good.