Are there roaming charges in Germany for UK or US SIM card users, considering Germany's EU membership and post-Brexit changes?

Germany is an EU member state, meaning 'Roam Like at Home' (RLAH) provisions apply to EU/EEA citizens. However, for UK and US SIM card users, the situation is different. Post-Brexit, many major UK carriers (e.g., O2, Vodafone, Three) have re-imposed daily roaming fees (typically £2-£6/day) for EU travel. US carriers like AT&T, T-Mobile, and Verizon often include basic international roaming, but frequently throttle data speeds or charge for full-speed access. CoreESIM offers dedicated local data at high speeds via German carriers like Deutsche Telekom or Vodafone Germany, providing a more predictable and cost-effective solution.