He is just playing GTO xD

Optimal poker is non obvious. Although it does make a lot of sense that a hand like 54ss which is total garbage on the turn and has no EV as a check back would be higher EV as an overbet unblocking folds and being able to bluff a lot of rivers. Not to mention that Llinus probably check raises flop wider than equillibrium leaving his turn range more capped than GTO, allowing OTB to overbet more aggressively.

I let the solver run to close to 0 exploitability on the turn and 54s non flushdraw is actually a pure strategy of bet, and overbetting is 3bb/100 better than checking. I think this hand illustrates a very important ability in poker which is being able to compare the EV of all the possible lines, which in the end is poker itself. Your poker skill is simply the sum of the accuracies with which you pick the highest EV strategic option in every single spot.

This hand illustrates that just because one option doesn't seem too good (overbetting turn with no equity) it doesn't mean you shouldn't take it because the other strategic options might just be even worse.

The main goal of bluffing any hand is to make a better hand fold. The combo that was chosen has no harmful card removal effects on linus folding region. So, as long bluffs are concern, this should be used somewhat frequently as long you keep your frequencies on track to don't bluff too much, specially against stations as linus =p

Great video by Ben Sulsky this one. Sauce does a great job explaining concepts surrounding this $200-$400 No Limit Hold’em hand played between OtB_RedBaron & Kanu7 as they battle Phil Ivey.