The indent appears as a "thin space" where the test chemical is. It is NEVER pink unless hcg has attached to the test chem. It usually appear gray, but very very faint lines are truly hard to see the pink on as well.
The indent also usually does not show when the test is FIRST taken. So if you saw that line right after urine added, and especially if it is really pink, not gray, then it is likely start of a bfp:
Check out the link below of hpt pics with betas- scroll down the pg and click frer, and you will see yours looks like the first couple pics.
GL it's a sticky!
https://www.peeonastickaddict.com/hpt-with-hcg/