[BIP-906] Deprecation of Polygon zkEVM, Fraxtal, and Mode

Summary

This proposal aims to deprecate Balancer support on three chains:

1. Polygon zkEVM - Full shutdown; all support ends at network EOL (Q2 2026)
2. Fraxtal - Degraded support; withdrawal-only functionality via portfolio page
3. Mode - Degraded support; withdrawal-only functionality via portfolio page

In line with BIP-887, no new Balancer v2 pools can be created on any network. This includes Fraxtal and Mode where only a v2 instance was rolled out. Combined with infrastructure limitations on these chains, this proposal formalizes the transition to minimal support while ensuring users retain the ability to withdraw their funds deposited in Balancer v2 pools.

Motivation

Polygon zkEVM

Polygon has announced the shutdown of the zkEVM network, scheduled for Q2 2026 (https://forum.polygon.technology/t/sunsetting-polygon-zkevm-mainnet-beta-in-2026/21020). As the underlying network will cease to exist, Balancer must deprecate all zkEVM support and communicate clear timelines to affected users.

Fraxtal

Following Fraxtal's gas token parameter changes, the existing v2 smart contracts have become semi-broken. Core functionality no longer operates as designed. Combined BIP-887 measures that prevent new v2 pool creation, continuing full support is not viable.

Mode

Mode Network has experienced declining infrastructure support, most critically the loss of reliable subgraph services. Without subgraph data, the protocol cannot accurately track pool states, calculate APRs, or provide users with essential analytics. As with Fraxtal, BIP-887 further restricts new v2 pool deployment.

Specification

Polygon zkEVM - Full Deprecation

Timeline: Network EOL in Q2 2026

Actions:

1. Mark zkEVM as deprecated in all systems
2. Display deprecation warnings on frontend
3. Maintain withdrawal functionality until network shutdown
4. Remove chain support completely at network EOL

Fraxtal and Mode - Degraded Support

Timeline: Effective immediately

Actions:

1. Mark Fraxtal and Mode as deprecated in all systems
2. Display deprecation warnings on frontend
3. Maintain withdrawal functionality

Core Requirement and Operational Constraints

At all times prior to full deprecation or network shutdown, users must retain the ability to safely and permissionlessly withdraw their funds from Balancer deployments on affected chains.

Support during deprecation or minimal-support phases is limited strictly to what is necessary to facilitate user exits. This level of support assumes only baseline chain accessibility (such as functional RPC endpoints, block explorers, and multisig access) and does not require full protocol infrastructure, active data indexing, or continued feature development. No guarantees are provided beyond enabling fund withdrawal and basic operational safety.

User Communication

Upon passage of this BIP:

1. In-app notifications displayed to users with positions on affected chains
2. Documentation updated to reflect deprecation status
3. Announcements made across official channels