Well, true enough.
I dont use mariadb either.
(I do have sqlite for the things that need it)
But it is used by default.
Akonadi and PIM are kinda resource hogs to begin with.
And we have known problems specifically because of the db in the past.
So … I’m thinking they do have those things and their mariadb is woefully out of date.
See example here:
If its not the source of the issue … it is likely not helping.
(and may be indicative of other issues. partial upgrade and all)