Thanks for your reply!
I did try the 'Fix this' button, but only got a pop-up with a message telling me to convert the database if I wanted to allow users to use some non-common symbols. To be honest, allowing some non-common symbols didn't seem to be an issue important enough to block an entire update.
There is a link in the last words of that message (to https://forum.verslavingdebaas.nl/admin/?app=core&module=support&controller=utf8mb4&_new=1 in my case) but that link does not work. You mentioned tools, is this message the tool you reffered to, or am I missing something important because the link does not work?
Thanks for the clarification of the InnoDB issue, I'll ask my host to start addressing it.