Preflop and earlier streets are fine, but the 15x-pot river shove as a bluff in a 3-way limped pot is massively over-aggressive and not credibly representing enough value.
Flop comes 8s Ah Jh, multiway, and we’re out of position in a limped pot—this very naturally goes check from us. Both opponents can have plenty of Ax, Jx, and strong heart draws from their limp ranges, while our specific hand has no pair and no made draw on this texture. In a 3-way pot we simply don’t want to start bluffing from OOP with such low equity; checking and mostly folding vs any reasonable bet is the correct bias. Our check here is totally fine.
Turn is 7d on 8s Ah Jh 7d, still 3-way and still checked to us. The board is getting more dynamic, but our specific hand is still just very weak with no made draw and no showdown value to lean on. Solvers in heads-up pots already slow down a lot in these low-equity, multiway-unfriendly spots; in an actual 3-way pot we should be even tighter about stabbing. Checking again and letting position play out is correct—there is no good reason to start a bluff line here.
River Th completes a 3-heart board: 8s Ah Jh 7d Th. After SB checks and we’ve checked twice already, the pot is still only 3BB and we shove 46BB into it 3-way. That’s the core problem: in a limped pot where we never showed strength on flop or turn, our line simply does not credibly represent enough very strong value to justify a 15x-pot polar shove. BU’s limp–check–check–check range easily contains many heart combos and other strong holdings that are happy to bluff-catch, while our specific hand has no blockers to those strong hands and zero showdown value to justify going for an ultra-polar line. Optimal play with this combo is to check and give up; if we ever bluff here at all, it should be at a much smaller size that can target weak one-pair and pure air. The all-in is a severe overbluff in a spot where ranges are wide and multiway and where our story does not add up.
Note: The 46BB shove into a 3BB pot on the river is far too large and unbalanced as a bluff in a 3-way limped pot; our range does not credibly contain enough strong value, while BU can easily have many strong hearts and other made hands that happily call.