Slight off topic here... but Ukrainian Flag draws obvious comparison to the mark of the beast in this case.

The main thing that's always been weird to me is how people treat 666 and "the number of the beast" in a similar way to "the mark of the beast" when it is completely unrelated.

The number of the beast is not "a number" written down but is like "a number of people". Demons form legions. A legion of demons is like the Holy Trinity in that we have 1 God in 3 Persons, except obviously an evil version. The whole "great satan" thing (avoiding for now the difference between the devil, the beast, satan, and other versions of "evil" and pretending wrongly that they are the same thing...) is hundreds of demons joining together to form 1 evil entity.

And no, it doesn't mean 666 demons form together. It means "a lot" of "very evil" demons form together. Jesus uses this concept in the Bible...

Then Peter came up and said to him, “Lord, how often will my brother sin against me, and I forgive him? As many as seven times?” Jesus said to him, “I do not say to you seven times, but seventy-seven times.

77 times is probably not actually correct, but is supposed to be 7 times 7 times. Which means "a lot of a good thing" times "a lot of a good thing". It essentially means "infinity good".

666 ergo means "infinity times infinity bad" in comparison.

Anyway, the point being there isn't just 1 "mark of the beast" there are many. The "I support the current thing" people are cycling through a bunch of them.