Some more information on Mrs. vs. Miss. becoming more curious I googled this morning.
This talks about the use of Mrs. historically: https://newrepublic.com/amp/article/119432/history-female-titles-mistress-miss-mrs-or-ms
This talks about the pronunciation switching from Mistress to Missis in the 18th century. https://www.grammarphobia.com/blog/2017/05/missus.html
Honestly, the change from mistress to missus sounds to me another way to bring women down beneath the level of men. Mrs. was previously used for women in power not marital status. It talks about eventually using mistress in lieu of missis/missus is perceived as quaint or pedantic Critical Pronouncing Dictionary of 1791, John Walker writes that “Mrs.” as “a title of civility” should be pronounced “missis,” and that to pronounce the word as “mistress” would “appear quaint and pedantick.” Still reminds me of the South and that using Missus Lastname can be perceived as uppity.
Plus, I think at least some of the time changes in pronunciation or usage happen either from illiteracy or people speaking a second language who are pronouncing similar to their first language or aren’t reading the word or they are using rules from their own culture.