Shouldn't the CRS port connected to the Deutsche Telekom fibre modem be set to VLAN 7 tagged
/interface bridge port add bridge=VLAN-Bridge1 frame-types=admit-only-tagged interface=sfp08-WAN-FTTH
/interface bridge vlan add bridge=VLAN-Bridge1 tagged=sfp01-Link_A1-RB4011,sfp08-WAN-FTTH vlan-ids=7
Not directly related:
/interface vlan add interface=VLAN-Bridge1 name=VLAN1-MGMT vlan-id=1 is almost always incorrect as the bridge-CPU interface uses VLAN 1 untagged by default
On a switch you do not need /interface vlan or the bridge-CPU interface to be a tagged member under /interface bridge vlan for any VLANs just passing through the switch, a single /interface vlan for management access from a VLAN is usually sufficient.
Adding untagged= membership under /interface bridge vlan is unnecessary as it dynamically added from the /interface bridge port PVID, this also prevents strange behaviour / communication problems if you change one but not the other when it has been added manually.
On newer versions of RouterOS adding tagged= membership under /interface bridge vlan is also unnecessary as it is dynamically added from /interface vlan attached to the bridge