Can a Jew report a Jewish business to 311 for not following COVID protocols?
I am assuming that the punishment for such violations is some form of fine / closure and not imprisonment. As such, it is by almost all accounts, permissible and does not fall into the category of moser. Added to this, there is an element of kiddush HaShem, given the public reporting of frum Jews violating these protocols – to have a frum Jew take them seriously is quite important.
This is not an issue of “none of your business,” since these violations endanger others. Even people that are volitionally choosing to patronize such establishments, can get the virus and then endanger others as a result.
I should say that if the store owner is Jewish, it could lead to a lot of friction and machloket, which would not only not be good for you, it might not be good for the community – it could create a split between those defending and those criticizing these establishments. That is your call. (I will note, that when Moshe Rabbeinu defended the Israelites against the Egyptian overlords, no one had a problem. But as soon as the following day he interjects himself into a dispute between two Jews and has the temerity to determine who is in the wrong and the רשע, and comes to the defense of the other – he is attacked and driven out of the country).
An excellent article that overviews the positions of mesirah in contemporary society where these is – at least in theory – just legal systems, was written by Rabbi Michael Broyde a number of years ago and can be found here – https://www.aishdas.org/avodah/vol05/v05n081.shtml#18