I only ever used Proton for a few secondary email accounts (compartmentalizing between personal and online) and I started transitioning shortly before they got in the news for statements.
My main problem was that I realized that I couldn't use email forwarding (or at least without paying for a plan, I forget), and I couldn't manually handle it with a third-party client without paying for their bridge, so unless I wanted to have to open and log in to an old email address for the rest of my life, I basically had to pay to deprecate an email address or move to another provider without risking any future emails to the protonmail address being lost, and I wasn't in a position where paying was an option for those addresses. Now I only register single-use throwaways on Protonmail (despite their efforts to detect and stop it).