Welcome to the forum Megan. 😊
I also use Thetford Pink toilet flush tank additive.
The online advertising blurb states that it creates a smooth protective coating on caravan toilet bowls and seals, it's said to prevent odours and limescale build up in the flush tank and it smells of lavender.
I can't guarantee that it lives up to it's claims, but with three or four weeks between caravan trips for us it's inevitable that some water will remain in the flush tank and hopefully the pink stuff keeps it ok.
Since Covid 19 and the closure and limitations on site facilities we've had at times to rely on our onboard facilities in all respects 💩
With the Thetford Blue concentrated bought in a double pack with the pink there have been no unpleasant odours, and even with frequent emptying the fluids last well and do their stuff for us.