I guess some of you have allready noticed that you sometimes get automatically transformed to a “supergroup” (no way back) which will provide you with additional features (activating one of them starting the convertion also 
The only usefull feature I guess for us is the ChatID+Topic stuff.
I simply tried to solve it the same way like here:
with some Blocky-Code
uid: telegram_with_chatID_topicID
tags:
- marketplace:131112
props:
parameters: []
parameterGroups: []
timestamp: Apr 4, 2024, 1:19:14 PM
component: BlockLibrary
config:
name: Telegram with ChatID+TopicID
slots:
blocks:
- component: BlockType
config:
args0:
- name: MESSAGE
type: input_value
- name: BOT
type: input_value
- name: CHAT_ID
type: input_value
- name: TOPIC_ID
type: input_value
colour: "#2ea5d8"
helpUrl: ""
inputsInline: true
lastDummyAlign0: right
message0: send on Telegram %1 from bot %2 with chat id %3 & topic %4
nextStatement: ""
previousStatement: ""
tooltip: ""
type: message
slots:
code:
- component: BlockCodeTemplate
config:
template: >
{{utility:things}}.getActions('telegram', {{input:BOT}}).sendTelegram({{input:CHAT_ID}}_{{input:TOPIC_ID}}, {{input:MESSAGE}});
toolbox:
- component: PresetInput
config:
fields:
TEXT: What's up?
name: MESSAGE
shadow: true
type: text
- component: PresetInput
config:
name: BOT
shadow: true
type: oh_thing
- component: PresetInput
config:
fields:
NUM: 123
name: CHAT_ID
shadow: true
type: math_number
- component: PresetInput
config:
fields:
NUM: 45
name: TOPIC_ID
shadow: true
type: math_number
utilities:
- component: UtilityJavaType
config:
javaClass: org.openhab.core.model.script.actions.Things
name: things
But it is not working. Could we Update the Binding to support such TOPIC_IDs ?