75%+ of my experience with howlongtobeat has seen me finish games in at least 1-2 hours less than the time they give. This makes sense, since a large amount of those who submit numbers do so based on playthroughs done on consoles, where the majority of games do not provide an exact time of completion. I've also seen this sentiment shared with a large amount of the players I interact with.
For example, check this page for Andromeda:
https://howlongtobeat.com/game.php?id=26802
It says that a completionist playthrough of the game averages around 90+ hours. That is completely insane and inflated. My normal playthrough of the game which ended at a 90% total completion (only things missing were a few miscellaneous objectives such as scanning all planets / crafting all Nomad upgrades, which in no way would take any more than 5 hours), and that took me exactly 50 hours.
Howlongtobeat also lists Doom 2016 as a 11 hours and a half game, yet I completed it in 9 hours. Same deal, even replayed a level once to get all collectibles.
Basically, Howlongtobeat numbers have always been inflated.