@StephaneB
I have a bit of my troubles here: Migration intégration Netatmo : plantage de Gladys - #4 par mutmut
and then there: Surconsommation de mémoire par le backup de gateway? - #18 par mutmut
For now, the only solution I found to no longer be bothered is to increase the RAM 
But as it’s a Proxmox cluster, if the host crashes, the LXC with Gladys will fail over to another host and then I risk having issues with shared RAM…
In any case, when it froze, I was able to unlock the situation by increasing the RAM live (thanks to LXC!), and all pending tasks completed successfully.