Apparently some tampons are certified flushable but not septic safe. Even with sewer services, the utility providing that service is not your landfill pickup, transport, and disposal company, so don't throw any solid waste in it. Also remember that even the liquid waste must be treated before it can be discharged or recycled, so don't go pouring all kinds of chemicals never intended for drains either.
Even if you don't care and your sewer utility allows you to flush, pipes often have buildup for certified "flushable" tampons to get stuck on and you will be paying a plumber to tell you not to flush them anyway.
Anyway, no mention of grease yet?
I worked for a high-rise condominium and one of the biggest issues we had was waste water backing up into an unoccupied unit any time people in the 18-story stack used their water. It had gone undiscovered for months (military deployment) only to be discovered after it began damaging units beside and below as well as the common areas (hallway, fitness room). The culprit was a grease ball far enough down the common drain that it could have been anyone. No tampon would have made it through it. In fact, it repeatedly absorbed the plumber's snakes as they would plunge in and out of a self-healing ball of grease. All they could do was repeatedly plunge it to break it up.
The small unit was absolutely horrifying. The sink and counter were one shiny black liquid surface of standing liquid sludge. The kitchen floor had a thick layer of sludge and the carpet was wet and black from just outside the kitchen and all the way through the living areas and into the bedroom.
My mother on the other side of the country had a similar issue with grease. She and her neighbors both rent from the same landlord and share a septic tank on her lot. She lives slightly downhill and sewage started backing out of her toilet one day. She frantically begged and pleaded with the neighbors to stop using their water but they just shrugged their shoulders and acted like "what are we supposed to do?" and kept doing their things. Uhh, for starters, you can try not dumping your feces and dishwater on the floor of my mother's home, while doing what it takes to get it fixed for the both of you, duh.

It's not like my mother needed her shower, sink, and toilet any less and yet she wasn't forced to use them. She should have asked them if she could crap on her own floor using their toilet while hers was unavailable just to rub in how ridiculous it was for them to think it's OK to keep dumping their feces in her home.
It turns out that they frequently deep fry their food and dump the grease/oil in the drain. Also, when I was a kid I recall seeing a PVC pipe that came up from the ground where we could observe any time the toilet was flushed. I now know that this was above ground level and below the home's plumbing level specifically so that backups would come up through it and not the home. I don't know how or when it disappeared, but I do recall the PVC being cracked up some time in the '90s. If they hadn't clogged it with grease and if that pipe were still there, it never would have happened.