3 Months into Russia's war against Ukraine: What to expect for the upcoming battles?

Russia's invasion of Ukraine has surprised many military analysts - who expected fighting to be over very quickly. Instead, the three-month-old war has exposed unexpected weaknesses in Russia's forces. Heavy troop losses are reporttedly hurting morale even more, and the war's initial aims have been severely scaled back. So just how - and why - has Russia's army performed so badly?