I see that SV Elversberg have been promoted to the Bundesliga. I’d never heard of them so did some research.
They had never played in the Bundesliga 3 until 2012-13 but they were relegated after one season.
They were playing in the Regionalliga as recently as 2021-22 when they were promoted to the Bundesliga 3, which they won at the first attempt.
They finished 11th in their first season and 3rd last season, but lost a play-off to Heidenheim. Now they have finished runners-up to Schalke to clinch promotion to the Bundesliga.
The town has a population of just 13,000 and their stadium holds less than 10,000. This is similar to the capacity of Holstein Kiel’s stadium in 2018 when they would have been denied a licence should they have won their play-off against Wolfsburg. They lost.
I don’t know whether Elversberg will be allowed to play in their own stadium. The closest alternative is Saarbrucken, 15 kilometres away. That holds just 16,000 but that would qualify under Bundesliga rules.