the use of widespread vaxxines will end up causing mutations
No, not at all.
The mutation is an error in the duplication of the initial data. This occurs all the time, statistically at a certain rate, just how the cell's machinery works. Time to time there's a miss, a wrong copy. Very often, actually in most of the cases, this error means the end of the road for a so simple structure like a virus, no longer functional. Once in a while (that comes down to a ridiculous low %), an error can be "life" compatible for the virus ("" because virus aren't living, truly speaking) and a new variant can spread around with this new data.
But the vaccine(s) has no hand at all on this process, contrary to mutagenic substances or radiations.
What does the vaccine is just to show to the immune system which enemy he has to fight. No more no less.
Then, if the immune system sees the enemy coming, it kills it.
But if the new version is significantly different from the "stock" one on the key areas (which the immune system learned to identify), the virus can pass by the guardian unattacked and be multiplied by the target cells.
So, the "stock" virus is killed and its global population tends to reduce. But the new one grows freely and spreads, until it's identified as a new threat by the immune system. That takes time though and meanwhile other people are contaminated. The process is repeated each time at the disadvantage of the stock virus and at the advantage of the new version.
In a widely vaccinated population, the old virus can't do much while the new one has an open field. Temporally though because the natural immunity (or a new vaccine) soon will target the new one and slow/reduce its progression. Until a new new version.
That's the way things work since forever, as for the flue. The vaccine reduces seriously the present wave, but doesn't prevent necessarily the future ones. Nor it makes a new one either.
The big advantage of the natural immunity is that one given virus can be identified by different molecular sites/combination, so a new one can still be possibly recognized. The usual vaccines play this card.
The m-RNA vaccine is very specific with one molecular site. Changes this target and it becomes useless. That's its downside, but I guess it may be faster and easier to produce and I find its principle quite elegant tough.
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