Just seen the 'Liberty Bar' episode, first series of the original UK Maigret, now showing (2022) on the 'Talking Pictures' channel in UK. As several have said, this episode is really poor, but I think it was intended as some (mild) comedy relief to others, as Rupert Davies repeatedly gets told he looks like the victim, and there are jokes about what an Australian (an early Paul Eddington) thinks of as normal French behaviour?! The victim had written a will to upset his family, a further attempt at (mild) humour I'd guess.
People viewing now should realise that TV was in its infancy when these were made, BBC had been going a few years, but ITV had only recently started. Just 2 channels, and they were only on for a few hours in the evening (apart from children's shows). So there just wasn't the TV acting expertise like there has been since, and some of the people in this one were awful, BUT you could argue that the direction was poor if the people playing to the back row of the Circle in a theatre weren't corrected to be less 'hammy'?
This series also tells the stories in just an hour, whereas the later Gambon versions (2 series, each of six episodes) were 90 minutes or so, and the several Rowan Atkinson 'one-off' shows were an indulgent 2 hours I think (& they required a bit of padding). Getting these ones done in an hour means they have to crack on, and there's not much time to replicate Simenon's way of having Maigret soak himself in the atmosphere of the crime, and getting inside the head of the main characters involved.
The film stock hasn't aged very well, so although the external shots were in France (later series were in Budapest?) the picture quality isn't great, and the studio scenes might have done with the same wobbly walls and doors that drew jokes about the likes of 'Compact' & 'Crossroads'. But that's how things were back then!!