Evidence from multiple major flashpoints shows that international military tensions did in fact escalate in Q4 2021 relative to earlier in the year:

• China–Taiwan: October 2021 set new records for Chinese military incursions into Taiwan’s air defense identification zone; one analysis notes that October became the busiest month on record and that the final quarter of 2021 saw a massive spike in such incursions, with 56 Chinese warplanes entering the zone on 4 October alone. These flights were widely framed by governments and media as destabilizing and escalatory behavior compared with previous months. (thediplomat.com)

• Russia–Ukraine: A renewed and “unusual” Russian troop buildup near Ukraine began in October–November 2021, with around 90,000–100,000 troops reported near the border and in occupied areas. NATO and Western officials publicly warned in mid‑November 2021 about a deteriorating security situation and the danger of further Russian aggression, and scholarship later labeled this period (October 2021–February 2022) a phase of renewed tensions preceding the 2022 invasion—distinct from and more ominous than the earlier 2021 buildup. (euronews.com)

• Ethiopia/Tigray and regional spillover risk: The Tigray war intensified and geographically expanded in late 2021. Tigrayan forces advanced south, capturing key towns such as Dessie and Kombolcha by the end of October and threatening a march on Addis Ababa, prompting a nationwide state of emergency. International organizations and media in November 2021 explicitly described the situation as an escalating war and warned it could destabilize the broader Horn of Africa. (en.wikipedia.org)

Taken together, these developments show a clear, measurable increase in international military tensions across several regions during Q4 2021 compared with earlier in 2021. That matches Friedberg’s qualitative prediction of “escalating global conflict” for that quarter, so the prediction is best judged as right.