As indicated in orbitmic's original post, Terminal 1 was always meant to shut from the second week of September. It was reopened temporarily to cope with the summer surge for a small handful of airlines (BA and Iberia in particular).

I did not find the Infinity lounge in T1 especially jammed compared to pre-covid days but I guess that these things are highly variable depending on when you are there. My own experience was that operations were slow due to the suspension of self-service but that lounge occupation as such did not seem worse than pre-covid, notwithstanding the concentration of all flights in T2.