It’s worth also considering the case of ski helmets. Since these have became common on the slopes head trauma has actually increased because wearers take more risks.
I see the possibility, but my own anecdotal experience with mask wearers and non-wearers jives with the other correlation: that non-wearers generally didn’t take the pandemic seriously.
The people that I know who shunned masks also ignored the COVID threat in other ways: Large gatherings, vacations to another state to escape lockdown restrictions, etc.
Whereas my religiously-masked friends were basically isolated last year.
And because I have several such anecdotes, I now have data :)
But feel free to wear a mask as much as you want, at this point it is effectively a security blanket though.
Pre-vaccination, I was an indoor-only wearer.
(I don't know either way, just curious to know if this angle has been investigated.)
After? Normal, but with masks.