In general, it’s not the most secure but it’s about your risk profile how secure you need and how you use it. Probably the most important security feature of BT is that it’s low power and short distance (quickly borrowing from a commercial site):
Encryption – All audio transfers are encrypted using encryption keys generated during the pairing process [but this encryption is not quaranteed with older BT versions and it’s not clear what your specific device would use]. The purpose of encryption is to protect the confidentiality of digital data transmitted between parties and preventing eavesdropping and unauthorised data access from third parties.
Intelligent Power – During the Bluetooth pairing process the power and range of the Bluetooth is reduced significantly. This makes helps protect devices from ‘man in the middle’ type attacks by making it extremely difficult to gain access without being in very close proximity.
Short Paring Window – Headsets [and other devices] are only discoverable for a short window during pairing. After that they turn off access until reactivated by the user. This means that the gaining access to pair with headset outside of this window is next to impossible without physical access to the devices.
So, you’re not insecure as such, but if you live in densely populated area/buildings (close to other people behind walls), don’t trust your environment and think you could be targeted, maybe consider using wired.
This kinda leads to another security point: if you have to keep BT open for keyboards and/or headphones, your security problem wouldn’t be just the connection with those or what’s transmitted but potential attacks to your computer via BT. It’s a beacon waiting for connection attempts. And speaking of beacons, there are ways to build amplified receivers/antennas for longer distance connections. It was already a decade ago that it was demonstrated that phone BT can be used to spy 3D location of persons in a building from some 100m/300ft. The “applied risks” are something that often go overlooked.
Want to dig deeper? See Bluetooth’s site Bluetooth Security | Bluetooth® Technology Website
There’s a good answer online for headsets that partly apply to OP question: Is it safe to use Bluetooth headphones? - Information Security Stack Exchange
A bit of BT sec: Bluetooth security risks to know + how to avoid them - Norton
And more: How to secure your Bluetooth devices | WIRED
And if you want to start on a rabbithole, here’s a recent BT vulnerability: https://medium.com/@hackersdump0/cve-2023-45866-a-critical-bluetooth-security-flaw-exploit-d2e0aec149fc (relevant to linux and keyboards)
Basics of BT spying: Introduction to How Bluetooth Surveillance Works | HowStuffWorks
And almost forgot that phone BT is used to track shoppers: Opinion | In Stores, Secret Bluetooth Surveillance Tracks Your Every Move - The New York Times
[bonus: Burglars Really Do Use Bluetooth Scanners to Find Laptops and Phones | WIRED]