Local public transport is mainly being paid for by the local county and city councils, who in turn are often relatively cash-strapped and cannot cover large revenue shortfalls on their own.
Local and regional mainline railway services are being paid for by the state governments, who however in turn are to a large extent relying on federal grants paid for that purpose [1].
The new ticketing scheme was instigated at the behest of the federal government, which has the biggest financing power, but has only pledged a limited (technically unlimited this year, but since the new ticketing scheme only became effective in May, it's very unlikely that the original fixed amount will be exceeded this year) amount for covering any revenue shortfalls up to 2025 (and strong-armed the states into pledging the same amount of money for that period, too).
So if it turns out that the combination of cheaper tickets, still present after-effects of the pandemic (i.e. loss of ridership and revenue) and current inflation means that losses are higher than expected, there's plenty of scope for finger-pointing and pushing the blame around, and at least localised service cuts in more cash-strapped cities and counties (respectively states, in the case of mainline railways) remain a possibility.
[1] Historically, local/regional services were operated and paid for by the then Federal Railways. When, in preparation for privatisation of the railways, the responsibility for contracting for/tendering of those services was transferred to the state governments, they also received a corresponding financial grant in return for taking on that responsibility. It might or might not have been the original intention, but in practice those federal grants are the main source of financing for local/regional mainline services to this day.