HTLC max in flight exceeded when sending LN payments

Tried to send about $100 to Coingate via LN. I have $400 in outgoing LN channel capacity across the Electrum and ACINQ trampolines.

Payment failed due to:

electrum/lnchannel.py
 952         if current_htlc_sum + amount_msat > chan_config.max_htlc_value_in_flight_msat:
 953             raise PaymentFailure(f'HTLC value sum (sum of pending htlcs: {current_htlc_sum/1000} sat '
 954                                  f'plus new htlc: {amount_msat/1000} sat) '
 955                                  f'would exceed max allowed: {chan_config.max_htlc_value_in_flight_msat/1000} sat')

Not sure why

• the LN router is choosing channels such that the channel limit are exceeded?
• trampolines are applying value in flight limits at all?

Start with the HTLC limit check shown in electrum/lnchannel.py around lines 952-955, then trace how LN routing selects channels and how trampoline payments reach this check. The issue does not name tests or define the intended behavior; done would require establishing why the limit is reached and validating the agreed behavior for routed and trampoline payments.