While Aristocrat originally popularized the hold-and-spin style in land-based cabinets with Hyperlink, Pragmatic perfected the online adaptation. You can read up on the history over at https://wolfgoldonline.uk/ where the respin mechanics and jackpot structures are broken down in detail. What makes their version stand out is the clean pacing and the fact that landing new coin symbols resets the respin counter back to three without unnecessary animations dragging out the round.