trust me its hard to know exactly what tree roots are invading a sewer
line, I had fitzers go around the hoiuse and straight down 7
feet.......

tree roots are easily and cheaply solved if you look at it as a ongoing
maintence item. I USED to have all sorts of trouble, after camera
inspection every joint but one had roots, line clogged constantly
including even under house.

tried root killer really pricey

didnt have money to replace entire sewer, about 10 grand near 10-% of
homes value and have to remove everything from my basement and garage.
when home was built in 1950 they added a lateral to drain water from
under slab........ all roots now.

every 3 months I dump 25 pounds of rocksalt in my washtub and add hot
water and stir. dissolve what I can, they go out of home for day the
salt kills the roots but doesnt hurt the trees. later washer loads
dissolve the leftover salt, contiuning the root killing

you can use water softener salt, or rock salt its cheaper here in snow
country.

cheap easy non hazardous, but always do before spring thats when roots
really grow.