Probably a student at UT. Antifa sympathizer.
One of the bombs - maybe two - were disguised as “For Sale” signs put in yards.
Another was on a bike/hike trail
Latest is at a Goodwill store.
Houses are high priced - because the quality of life is good - when people move they often donate old furniture and things to Goodwill rather than taking them.
This has to do with real estate. Someone is trying to mess with Austin real estate prices.
That’s my guess.