I don't know why you're getting downvoted negative, unless people just aren't following what's happening in Ukraine. I know it's difficult. I have to follow multiple Telegram sources, so it's very forgivable.

First, re: sources.

• TGP is not a source. Ever. It is a clickbait leech site that takes other people's work and mainly a bunch of Tweets and tries to pass it off as news while they run you through a circle jerk of their own links if God forbid you ever want to track down original source information. It is a cancerous, evil website.
• ISW (Institute for the Study of War) is a think tank populated by retired military brass and Neocons. They have extremely good insider access to raw data and the Pentagon's interpretation/analysis of it. But their own bias is globalist and pro-interventionist, and they frequently toe the pro-war anytime anywhere line a bit like Lindsay Graham. It's worth listening to their facts, but do your own thinking about how to interpret them.
• Sources I use: Douglas MacGregor, Scott Ritter publishes at consortiumnews.com, YT summaries (10-20 min daily videos: Military Summary (Dima, a Belorussian), Weeb Union, Telegram (рыбарь, Intel Slava Z, Intel Republic, Slavyangrad). I'm including the two YT sources because both do an excellent job of watching both Ukr and Rus social media far more than I ever could and are committed to neutral presentation of facts.

Second, you're absolutely right on the situation at Avdiivka.

• Due to its geographical location on several supply lines, it has become a major defensive point seen as a key Ukrainian foothold in Donbas (one of the 4 breakaway regions now annexed by Russia). Russia intends to consolidate it because it is key to defending the land bridge from Russia to Crimea. It's not negotiable for them.
• Ukraine knows this and after Bakhmut/Artemovsk fell to Wagner, they turned Avdiivka into a fortress: trenches, pre-formed concrete pill boxes, tunnels, etc. It's going to be every bit as ugly to clear as Mariupol's Azov Steel factory and Bakhmut were.
• Russia has brought in the reintegrated Wagner veterans to lead their infantry assaults and are pairing them with tanks, brand new T-90s. They're well-supplied, but they're getting ripped up by accurate long-range artillery fire, which is why you're hearing about those casualty numbers.
• You have to remember that this fight is playing out under 24/7 high-res satellite and drone surveillance from both sides. Nothing moves on that battlefield without both sides being acutely aware of it and using that data in a coordinated way to target their artillery.
• This is defender's war, which is why, thus far, Russia has been winning decisively. When they go on the offensive, Ukraine gets to play defense. They get to use all of those guerrilla tactics the NATO boys have been teaching them. It's what Ukraine should have done from the start, honestly.
• What I've noticed is the continued absence of air power. Russia still hesitates to put much more than a few choppers up opportunistically to hunt tanks because of the SAM systems. Despite all of the missile strikes on radar and mobile SAM systems, Ukraine's still got enough to credibly threaten Russian air power. We're not even seeing their flagship stealth SU-57. They're fielding their 4th gen planes when they drop their FAB and various air-launched cruise missiles.

What do I expect?

Russia's going to have to flatten the city. There's no other choice. They've cauldroned the troops, surrounded the city and can attack from 3 sides. They've got fire control (artillery range) over their supply lifeline to the west. So, this is effectively a siege and the question will be whether they can resupply via tunnels or something. But yeah, expect this to be slow, methodical, and bloody. Russia's going to make the rubble bounce like a rave.